Statement I: The blue colour of copper sulphate crystal disappears when it is heated strongly. Statement II : Due to heating, water of crystallization of crystal is lost.

Copper sulphate crystals (CuSO4·5H2O) possess a characteristic deep blue colour due to the presence of water of crystallization [1]. When these crystals are heated strongly, the water molecules that are chemically bonded within the crystal lattice are evaporated and lost to the surroundings [1]. This process of dehydration converts the hydrated salt into anhydrous copper sulphate (CuSO4), which is a white, powdery substance [1]. Consequently, the blue colour disappears as the structural water molecules, which were responsible for the specific light absorption and colour of the crystal, are removed. Therefore, Statement I is true regarding the colour change, and Statement II is true as it correctly identifies the loss of water of crystallization as the underlying cause for this transformation [1].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 2: Acids, Bases and Salts > Activity 2.15 > p. 32